[BOLT] Ignore PC-relative relocations from data to data

BOLT expects PC-relative relocations in data sections to reference code
and the relocated data to form a jump table. However, there are cases
where PC-relative addressing is used for data-to-data references
(e.g. clang-15 can generate such code). BOLT should recognize and ignore
such relocations. Otherwise, they will be considered relocations not
claimed by any jump table and cause a failure in the strict mode.

Reviewed By: yota9, Amir

Differential Revision: https://reviews.llvm.org/D123650